util/hash_table: replace _mesa_hash_data's fnv1a hash function with xxhash

For most key sizes, xxhash outperforms fnv1a's hash rate substantially (bug
2153). In particular, the V3D driver hashes multiple ~200 byte keys as part
of the shader cache lookup which can easily eat up 10-20% of the runtime on
the Raspberry Pi. Swapping over to xxhash drops this to ~1% of the runtime.

Reviewed-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3475>

diff --git a/src/util/hash_table.c b/src/util/hash_table.c
index 9d98270886867e088b369fe691d53f46a104653c..48d59e48431561db671d3cfdc3582eb7efc1f4a5 100644 (file)
--- a/src/util/hash_table.c
+++ b/src/util/hash_table.c
@@ -50,6 +50,9 @@
 #include "main/hash.h"
 #include "fast_urem_by_const.h"
 
+#define XXH_INLINE_ALL
+#include "xxhash.h"
+
 static const uint32_t deleted_key_value;
 
 /**
@@ -549,8 +552,7 @@ _mesa_hash_table_random_entry(struct hash_table *ht,
 uint32_t
 _mesa_hash_data(const void *data, size_t size)
 {
-   return _mesa_fnv32_1a_accumulate_block(_mesa_fnv32_1a_offset_bias,
-                                          data, size);
+   return XXH32(data, size, 0);
 }
 
 /** FNV-1a string hash implementation */